In recent years, a new Flat Panel Display (FPD) industry has been developing rapidly. High demand of consumers on large-sized, high-resolution flat panel display stimulates the whole industry to continuously upgrade a display technology. As a core technology of the FPD industry, a Thin Film Transistor (TFT) array substrate technology is also undergoing profound changes. A Metal Oxide Thin Film Transistor (MOTFT) not only has high mobility, but also has simple fabrication process, low production cost, and excellent uniformity in large area. Therefore, the MOTFT technology has attracted much attention in the industry since its inception.
Representatives of metal oxide semiconductor include, for example, Indium Gallium Zinc Oxide (IGZO) and Indium Zinc Oxide (IZO). But a mobility of IGZO is still not high enough, about 10 cm2/V·s. A mobility of IZO is higher than that of IGZO, but it has more oxygen vacancies and a high concentration of free carrier, resulting in that a TFT device is hard to be turned off, and has poor stability.
Generally, the oxygen vacancies may be reduced by using a method of processing a surface of a metal oxide with oxygen plasma, but in one aspect, this method can only improve the oxygen vacancies on the surface of the metal oxide. In another aspect, the oxygen plasma has large energy, the oxygen vacancies may be increased by bombarding the surface of the metal oxide. Therefore, the method of processing the surface of the metal oxide with the oxygen plasma has limited effects in improving the oxygen vacancies.